This invention relates to a method of maintaining clean surfaces for valve seat faces in internal combustion engines to be used in motor cars and other vehicles.
Up to the present time, an inlet port and an exhaust port are formed on a cylinder head in which a piston reciprocates. These ports open and close in turn by the operation of the relative valves linked with said piston. An inlet valve is seated on the inlet port while an outlet valve is seated on the exhaust port. Valve seat face and valve face which contact each other are highly ground and polished so that good sealing can be obtained thereon.
After burned gases are ejected by the cylinder, in this exhaust gas, incomplete combustion materials exist, which are caused by plural factors such as incombustibles included in the fuel, or carbon, water and other substances generated by combustion. The carbon, acid and other similar substances which result from the incomplete combustion materials react with calcium, zinc, phosphorus, magnesium and other elements included in additive agents of lubricant oils during combustion, and this reaction produces some solid particles. On the other hand, in the lubricant oil, there exist impurities included in the fuel and metal dust on the inner surface of the cylinder, shafts and bearings. When these solid particles, impurities and metal dust are adhered on the valve faces or the valve seat faces, it badly damages the faces and sealing is lost, and this allows gas to escape partially and results in the deterioration of engine compression. This deterioration is a bad influence on combustion efficiency and increases specific fuel consumption thereof, while in case of a motor car the function of engine braking is remarkably lowered.
The additive agents used in the lubricant oils are detrimental when their original role is fulfilled. It is very important to maintain the engine performance to overcome the explained situations, so that it may promote the engine quality and realize the economization of the fuel consumption as well as it maintains the good engine braking through the prevention of the bad influences caused by the adherence of the solid particles and metal dust on the valve faces and the valve seat faces, which are generated and invited by the reaction between the incomplete combustion and the additive agents included in the lubricant oils.
In the past, the deterioration of the engine compression which brings worse fuel consumption and inferior engine braking was generally believed to be dependent upon hysteresis of a liner fatigue or a ring fatigue.
According to the knowledge of this inventor, however, the source of this deterioration is mainly due to the solid particle and metal dust adhered on the valve faces or the valve seat faces, not by the hysteresis.